Sealing structure



April 28, 1964 K. scHLbR 3,130,900

SEALING STRUCTURE Filed March 7, 1962 INVENTOR. KARL EIEHLDR v ATTORNEYUnited States Patent O 3,1393% SEALING STRUQTURE Karl Schir, Lochham,near h innich, Germany, assignor to NSU MotorenwerireAirtiengesellschaft, Neckarsulm, and Wankel G.ni.b.H., Lindau(Bodensee), Germany Filed Mar. 7, 1962, Ser. No. 178,113 Claimspriority, application Germany Mar. 8, 1961 3 Claims. (QB. 230-145) Thisinvention relates to sealing structures of the kind used in conjunctionwith rotary mechanisms, such as combustion engines, compressors, pumps,or expansion engines.

The invention is particularly useful in connection with rotarycombustion engines similar to that disclosed in US Patent No. 2,988,065.

Such a rotary combustion engine comprises an outer bodybaving a cavitytherein and an inner body relatively rotatable within said cavity, aboutan axis laterally spaced from but parallel to the axis of said cavity.The outer body has axially-spaced end walls and a peripheral wallinterconnecting the end walls to form said cavity, the inner surface ofthe cavity peripheral wall having a multilobe profile which preferablyis basically an epitrochoid. The inner body has end faces disposedadjacent to said outer body end walls for sealing cooperation therewithand has a peripheral surface with a plurality ofcircumferentially-spaced apex portions, each carrying a radiallymovableseal for sealing engagement with the multi-lobe inner surface of theouter body peripheral wall to form a plurality of working chambersbetween the two bodies which vary in volume upon relative rotation ofthe two bodies. Each such apex seal of the inner body runs axially fromone end face to the other of the inner body. The number of apices willusually exceed the number of lobes of the epitrochoid by one.

In the subsequent discussion it will be assumed that the inner body isrotary whereas the outer body is stationary. Accordingly, the inner bodywill be identified as the rotor and the outer body as housing. It willbe appreciated, however, that the considerations applicable to the priorart as well as to the described invention apply equally in thesituations where the relations of inner and outer body are inverted, orwhere both inner and outer body may be rotating as described in thementioned Patent 2,988,065.

Each apex seal is seated in a slot or groove that is provided at thecorresponding apex of the inner body, with play in both the radial andalso the peripheral or lateral directions. One or the other of the sidesurfaces of the seal engages its confronting slot side wall with surfacecontact, depending upon the relative pressures prevailing in theadjacent chambers.

Let the working chambers, sealed off from one another by a given apexseal, be designated by A and B. Let the given pressures prevailing inchambers A and B also be designated as A and B respectively. The sealhas exposed parts, namely the part which projects radially outwardly ofthe rotor body and the two end parts which project axially outwardly ofthe rotor body. These exposed parts are subject to the pressures A and Bat respective side walls of the seal. If pressure A exceeds pressure B,the seal assumes one position in which the seal side wall adjacentchamber B engages its confronting slot side wall with surface contact.If pressure B exceeds pressure A, the seal assumes an alternate positionwherein the seal side wall adjacent chamber A engages its confrontingslot side wall with surface contact. In the operation of the engine therelation of pressures A and B changes, pressure A exceeding pressure Bfor some portions of the engine cycle and pressure B exceeding pres-3,130,900 Patented Apr. 28, 1964 'ice sure A for other portions of theengine cycle. Accordingly the seal repeatedly shifts from one positionto the other to follow the relative magnitudes of pressures A and B.

One problem with such apex seal structure is to assure sealing atoperating engine temperatures. It has been found with prior art apexsealing structures that due to differential expansion of housing, rotorand seal, sealing engagement is not maintained by the seal at all thesealing surfaces, namely the housing peripheral wall and also the twohousing end walls. Another problem is maintaining the seal in one or theother above-described desired positions in which seal side wall engagesslot side wall with surface contact. It has been observed that apexseals tend to tilt within the slot in the course of engine operation, sothat the seal-to-slot contact is reduced from surface contact to linecontact, thereby further reducing sealing efficiency.

The present invention is directed to the solution of these problems andcontemplates a novel seal structure meeting this objective. Inaccordance with the invention, the seal has a laterally (peripherally)extending throughopening at its underside, a pair of jaw-like, end legparts which are of symmetrical construction and location, and a middlepart wedged between the end leg parts, the interior surfaces of theseparts defining the through-opening. The end leg parts are split from themiddle part along a pair of splitting planes which are symmetrical withrespect to the transverse (latterally extending) median plane of theseal and which converge to common intersection with such median planeand with each other, radially outwardly and axially inwardly. The verysame splitting planes also define the mentioned interior surfaces of theend legs. This construction assures freedom of the parts to moverelative to one another both axially and radially to assure engagementby the seal of the housing peripheral wall as well as its end wallsunder conditions of thermal expansion of seal, rotor, and housing atoperating temperature of the engine. Moreover, since the splits betweenseal parts extend to the contact line between seal and housingperipheral wall, the seal parts are also free to move in the lateral(peripheral) direction relative to each other, even at such contactline. Hence merely one seal part need be subject to tilting effects,which are due to localized frictional binding at the contact line andtherefore temporary, the other seal parts assuming or retaining theircorrect dispositions for surface contact with slot side walls.

Within the mentioned through-opening of the seal there is preferablydisposed a resilient member which engages the mentioned interior surfaceof each of the three seal parts so as to urge these seal parts topositive sealing engagement with the respective interior housing walls.More particularly, the middle part of the seal experiences urging in theradial direction, whereas the end parts have urging force components inboth the axial and radial directions. In a preferred embodiment of theinvention the resilient member is arcuate in shape, the are beingtangent to the inter engaged, seal-part surfaces.

For a better understanding of the invention, reference is made to thefollowing more detailed specification of which the appended claims forma part, when considered together with the accompanying drawing, inwhich:

FIG. 1 is a fragmentary, axial sectional view, taken along line 1-1 ofFIG. 2, of an apex portion of an engine rotor carrying apex sealstructure in accordance with a preferred embodiment of the invention;and

FIG. 2 is an end view of the engine rotor of FIG. 1, being partly insection, taken along line 2-2 of FIG. 1.

Referring to FIGS. 1 and 2, there is shown the apex portion of a rotor1a, whose plural apices (FIG. 2) engage the interior peripheral housingwall 11) of the engine in sealing relation by means of plural apex seals10, carried by rotor 1a at the apices. The profile of housing 1b ispreferably basically a multi-lobed epitrochoid, and the number of apicesof rotor 1a will exceed the number of lobes by one. The rotor 1a rotateseccentrically within housing 117 in the manner described in theintroductory part of the specification. The apex seals project axiallyfrom the rotor end walls and engage the epitrochoidallyshaped interiorend walls (not shown) of housing 1b in sealing relation.

As may best be seen in FIG. 1, the apex seal is composed of a pair ofjaw-like, end leg parts 2, 4, and a middle part 3 which is wedgedbetween the end leg parts 2, 4. The parts 2, 4 are symmetrically locatedand constructed with respect to the transverse (laterally extending)median plane defined by section line 2-2. The interior surfaces of parts2, 3, 4 define a laterally (peripherally) extending through-opening atthe seal underside. End leg parts 2, 4 are split from middle part 3along a pair of splitting planes 5, 6 which are symmetrical with respectto transverse median plane 22 and which converge to common intersectionwith such median plane and with each other, radially outwardly andaxially inwardly. Moreover, splitting planes 5, 6 also define thementioned interior surfaces of end legs 2, 4.

Seated within opening 7 is a leaf spring member 8 of arcuate or bowedshape, which engages the interior surfaces of seal parts 2, 3, 4tangentially so as to urge part 3 radially outwardly, and parts 2, 4 inboth the radial and axial directions to sealing engagement with thehousing peripheral and end walls. Opening 7 is in pressure communicationwith one or the other adjacent working charn bers, whichever has thegreater pressure. Communication with the working chamber at lowerpressure is sealed off by the seal in response to the higher of the twopressures. The pressure admitted to opening 7 impinges on the interiorsurfaces of parts 2, 3, 4 and serves to :urge them to sealing engagementwith the peripheral and end walls of housing 1b in the same manner asspring 8.

The seal parts 2, 3, 4, as well as the spring 8, are disposed inside twospaced and substantially U-shaped guide parts or retainers 9 and 10 (seealso FIG. 2) with the ends of the spring 8 bearing against the members9, 10 at approximately the valleys of the U as shown in FIG. 1. Themembers 9, 1d) are shaped to form a plurality of steps 9a, 9b, and 10a,10b (FIG. 1), and 1%, 10d (FIG. 2) to assure stability of seating withinthe rotor; correspondingi'steps 9c, 9d are not visible in FIG. 2. Themembers 9, 10 are symmetrical in construction and location. As shown inFIG. 2, the guide parts 9, 1d are provided with grooves 11 to receivethe usual side or end seals 12 of the rotor, which with the apex seals,serve to seal 01f adjacent working chambers from one another. The guideparts 9, 10 are axially movable and in sealing engagement with theadjacent end walls of the outer body.

While the invention has been described by one specific embodiment, itshould be understood that this invention is not limited to specificdetails of construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the artwithout departing from the spirit of the invention.

What is claimed is:

1. In a rotary mechanism of the kind comprising an outer body having acavity therein and an inner body relatively rotatable within said cavityabout an axis laterally spaced from but parallel to the axis of saidcavity, said outer body having axially-spaced end walls and a peripheralwall interconnecting the end walls to form said cavity, the innersurface of the cavity peripheral Wall having multi-lobe profile which isbasically an epitrochoid, said inner body having end faces disposedadjacent to said outer body end walls for sealing cooperation therewithand having a peripheral surface with a plurality ofcircumferentially-spaced apex portions, said inner body being providedat each apex with a through-slot that extends axially from one of itsend faces to the other, each such slot being defined by a pair of sidewalls, an apex seal member seated in each said slot with play in boththe radial and circumferential directions and engaging the multi-lobeinner surface of the outer body peripheral wall and also itsaxially-spaced end walls in sealing relation to form a plurality ofworking chambers between the two bodies which vary in volume uponrelative rotation of the two bodies, normally different respective gaspressures prevailing in said working chambers during operation of saidrotary mechanism, each said sealing member having: a pair of axiallyextending side walls which confront the side walls of the respectiveslot, a laterally extending through-opening at the seal underside, apair of jaw-like, end leg parts, and a middle part wedged between theend leg parts, the interior surfaces of these parts defining thethrough-opening, said end leg parts being split from the middle partalong a pair of splitting planes which converge to intersection withreference to the inner body center radially outwardly and axiallyinwardly, said splitting planes also defining the mentioned interiorsurfaces of the end legs, whereby said parts are freely movable relativeto each other in the lateral direction, even at the contact line betweenseal and the interior peripheral wall of said outer body, and are alsofree to move relative to one another in the axial and radial directions.

2. The invention according to claim 1, further provided with a resilientmember seated within each through-opening, each such resilient memberbeing of arcuate shape and engaging the aforesaid interior surfaces ofthe parts of a given seal tangentially so as to urge the seal to engageWith the interior peripheral wall and also the end walls of the outerbody for sealing engagement therewith.

3. The invention according to claim 2, further provided with a means forretaining each seal member and its resilient member, being seated in theinner body, at least in part radially inwardly of the respectiveresilient member with reference to the inner body center and bearingagainst the free ends of such resilient member.

References Cited in the file of this patent UNITED STATES PATENTS394,242 Byers Dec. 11, 1888 1,280,306 Rolafr Oct. 1, 1918 2,801,791Walter Aug. 6, 1957 3,064,880 Wankel Nov. 20, 1962 FOREIGN PATENTS590,085 France June 10, 1925

1. IN A ROTARY MECHANISM OF THE KIND COMPRISING AN OUTER BODY HAVING ACAVITY THEREIN AND AN INNER BODY RELATIVELY ROTATABLE WITHIN SAID CAVITYABOUT AN AXIS LATERALLY SPACED FROM BUT PARALLEL TO THE AXIS OF SAIDCAVITY, SAID OUTER BODY HAVING AXIALLY-SPACED END WALLS AND A PERIPHERALWALL INTERCONNECTING THE END WALLS TO FORM SAID CAVITY, THE INNERSURFACE OF THE CAVITY PERIPHERAL WALL HAVING MULTI-LOBE PROFILE WHICH ISBASICALLY AN EPITROCHOID, SAID INNER BODY HAVING END FACES DISPOSEDADJACENT TO SAID OUTER BODY END WALLS FOR SEALING COOPERATION THEREWITHAND HAVING A PERIPHERAL SURFACE WITH A PLURALITY OFCIRCUMFERENTIALLY-SPACED APEX PORTIONS, SAID INNER BODY BEING PROVIDEDAT EACH APEX WITH A THROUGH-SLOT THAT EXTENDS AXIALLY FROM ONE OF ITSEND FACES TO THE OTHER, EACH SUCH SLOT BEING DEFINED BY A PAIR OF SIDEWALLS, AN APEX SEAL MEMBER SEATED IN EACH SAID SLOT WITH PLAY IN BOTHTHE RADIAL AND CIRCUMFERENTIAL DIRECTIONS AND ENGAGING THE MULTI-LOBEINNER SURFACE OF THE OUTER BODY PERIPHERAL WALL AND ALSO ITSAXIALLY-SPACED END WALLS IN SEALING RELATION TO FORM A PLURALITY OFWORKING CHAMBERS BETWEEN THE TWO BODIES WHICH VARY IN VOLUME UPONRELATIVE ROTATION OF THE TWO BODIES, NORMALLY DIFFERENT RESPECTIVE GASPRESSURES PREVAILING IN SAID WORKING CHAMBERS DURING OPERATION OF SAIDROTARY MECHANISM, EACH SAID SEALING MEMBER HAVING: A PAIR OF AXIALLYEXTENDING SIDE WALLS WHICH CONFRONT THE SIDE WALLS OF THE RESPECTIVESLOT, A LATERALLY EXTENDING THROUGH-OPENING AT THE SEAL UNDERSIDE, APAIR OF JAW-LIKE, END LEG PARTS, AND A MIDDLE PART WEDGED BETWEEN THEEND LEG PARTS, THE INTERIOR SURFACES OF THESE PARTS DEFINING THETHROUGH-OPENING, SAID END LEG PARTS BEING SPLIT FROM THE MIDDLE PARTALONG A PAIR OF SPLITTING PLANES WHICH CONVERGE TO INTERSECTION WITHREFERENCE TO THE INNER BODY CENTER RADIALLY OUTWARDLY AND AXIALLYINWARDLY, SAID SPLITTING PLANES ALSO DEFINING THE MENTIONED INTERIORSURFACES OF THE END LEGS, WHEREBY SAID PARTS ARE FREELY MOVABLE RELATIVETO EACH OTHER IN THE LATERAL DIRECTION, EVEN AT THE CONTACT LINE BETWEENSEAL AND THE INTERIOR PERIPHERAL WALL OF SAID OUTER BODY, AND ARE ALSOFREE TO MOVE RELATIVE TO ONE ANOTHER IN THE AXIAL AND RADIAL DIRECTIONS.